Research on a Comparative Study between UPFC and DPFC in a Grid Connected Wind Turbine System

Abstract

In the evolving landscape of renewable integration, voltage instability and reactive power mismatch pose significant challenges, particularly in wind-integrated power systems. To address these issues, Flexible AC Transmission Systems (FACTS) devices offer a robust solution. This paper provides a comparative study between two advanced FACTS controllers: the Unified Power Flow Controller (UPFC) and the Distributed Power Flow Controller (DPFC), integrated within a grid-connected wind turbine setup. The simulation is performed using MATLAB/Simulink, with emphasis on voltage stabilization, power quality enhancement, and harmonic mitigation. The UPFC model, utilizing 48-pulse converters and centralized control, shows its traditional strength in dynamic voltage control and reactive power compensation. In contrast, the DPFC architecture decentralizes the functionality of UPFC by replacing the common DC link with distributed single-phase D-STATCOMs and a central series converter, enhancing modularity and reducing installation costs and electromagnetic interference.

Introduction

The text discusses the growing importance of wind energy in the global shift toward renewable power, while highlighting the challenges it creates for grid stability due to its intermittent and variable nature. To address issues such as voltage fluctuations, reactive power imbalance, harmonics, and system instability, Flexible AC Transmission Systems (FACTS) are used, particularly the Unified Power Flow Controller (UPFC) and the Distributed Power Flow Controller (DPFC).

UPFC is a powerful centralized device that controls voltage, impedance, and power flow using shunt and series converters connected through a DC link. However, it is costly and complex, making it less suitable for modern decentralized smart grids. In contrast, DPFC improves on this design by distributing control across multiple converters, making it more modular, scalable, cost-effective, and fault-tolerant.

The study compares UPFC and DPFC using MATLAB/Simulink under realistic conditions such as varying wind speeds, load changes, and grid faults. The evaluation focuses on voltage regulation, reactive power support, harmonic reduction, and overall system stability. Results show that UPFC provides strong centralized control for large systems, while DPFC performs better in distributed grid environments.

The literature review supports this comparison by covering key developments in FACTS technology, power system stability, renewable energy integration, and control strategies like STATCOM, MPPT, and predictive control. Previous studies highlight both the effectiveness and limitations of different FACTS devices and emphasize the need for improved, scalable solutions.

Conclusion

This study has successfully compared the performance of Unified Power Flow Controller (UPFC) and Distributed Power Flow Controller (DPFC) in a grid-connected wind turbine system. The findings indicate that while both controllers enhance voltage stability and power quality, DPFC exhibits superior performance in reducing harmonic distortion, providing phase-wise compensation, and maintaining voltage symmetry. Its distributed architecture allows for more flexible and responsive control, making it better suited for dynamic and renewable-integrated power grids. UPFC, though robust, is less adaptable and introduces higher implementation complexity. In summary, DPFC emerges as a more efficient and scalable solution for modern grid applications.

References

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Copyright

Copyright © 2026 Tushar More, Pradumna Gawali, Hariom Chavan, Chetan Thakare, Prof. A. S. Lahane. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.